TY - JOUR
T1 - The adsorption of oxygen on NiAl(001) at 300 K and 20 K
AU - Franchy, R.
AU - SO, Shu Kong
AU - Gaßmann, P.
N1 - Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 1996
Y1 - 1996
N2 - The adsorption of oxygen on NiAl at 300 K and 20 K has been studied by means of high resolution electron energy loss spectroscopy (EELS), low energy electron diffraction (LEED) and Auger electron spectroscopy (AES). The adsorption of oxygen at 300 K leads to formation of a thin film of amorphous aluminum oxide (a-Al2O3). After oxygen adsorption at 300 K and annealing of the oxygen-saturated surface to 1200 K, a well-ordered thin θ-Al2O3 film is formed. After annealing of the oxygen-saturated surface to 1400 K, an α-like Al2O3 oxide is grown. Even at 20 K oxidation of the NiAl(001) surface is found. However, at higher exposure (≥ 5 L) oxygen physisorbs and the EEL spectrum exhibits characteristics of resonance scattering. The resonance energy for physisorbed oxygen on the amorphous Al oxide layers formed at 20 K has a value of 7.0 eV. The frequency of O-O stretching vibration for physisorbed O2 is 193 meV. The line shape of this mode is asymmetric with a pronounced tail on the high energy side. The asymmetric line shape corresponds to multiple losses due to the overlap of the O-O stretching mode with low frequency modes. After physisorption of oxygen at 20 K on the α-like Al oxide layers, the resonance energy is shifted to 9.0 eV, a value close to that of oxygen in the gas phase.
AB - The adsorption of oxygen on NiAl at 300 K and 20 K has been studied by means of high resolution electron energy loss spectroscopy (EELS), low energy electron diffraction (LEED) and Auger electron spectroscopy (AES). The adsorption of oxygen at 300 K leads to formation of a thin film of amorphous aluminum oxide (a-Al2O3). After oxygen adsorption at 300 K and annealing of the oxygen-saturated surface to 1200 K, a well-ordered thin θ-Al2O3 film is formed. After annealing of the oxygen-saturated surface to 1400 K, an α-like Al2O3 oxide is grown. Even at 20 K oxidation of the NiAl(001) surface is found. However, at higher exposure (≥ 5 L) oxygen physisorbs and the EEL spectrum exhibits characteristics of resonance scattering. The resonance energy for physisorbed oxygen on the amorphous Al oxide layers formed at 20 K has a value of 7.0 eV. The frequency of O-O stretching vibration for physisorbed O2 is 193 meV. The line shape of this mode is asymmetric with a pronounced tail on the high energy side. The asymmetric line shape corresponds to multiple losses due to the overlap of the O-O stretching mode with low frequency modes. After physisorption of oxygen at 20 K on the α-like Al oxide layers, the resonance energy is shifted to 9.0 eV, a value close to that of oxygen in the gas phase.
UR - http://www.scopus.com/inward/record.url?scp=0008677904&partnerID=8YFLogxK
U2 - 10.1142/s0218625x96002825
DO - 10.1142/s0218625x96002825
M3 - Journal article
AN - SCOPUS:0008677904
SN - 0218-625X
VL - 3
SP - 1909
EP - 1917
JO - Surface Review and Letters
JF - Surface Review and Letters
IS - 5-6
ER -